Valeant CEO Mike Pearson will be on medical leave

Michael Pearson, chairman of the board and CEO of Valeant Pharmaceuticals International Inc. Thomson Reuters

Valeant Pharmaceuticals International Inc. announced on Monday that its CEO J. Michael Pearson would take a medical leave of absence, effective immediately.

"The company's board of directors has created an office of the chief executive officer, which will include Robert Chai-Onn, executive vice president and general counsel; Dr. Ari Kellen, executive vice president and company group chairman; and Robert Rosiello, executive vice president and chief financial officer, to serve in an interim capacity," the company said in a press release.

"Our thoughts are with Mike and his family," Valeant board member Robert Ingram said. "Out of respect, we will be honoring his family's request for privacy and will not be commenting further on his condition at this time."

Shares of Valeant stock fell 9% after the news.

Pearson, 56, joined Valeant as CEO in September 2010 after a 23-year career at McKinsey & Company, and he became chairman of the board in 2010.

Pearson's illness comes as investors are turning up pressure on the Canadian drugmaker to provide a more detailed plan on how it will grow profits in 2016. Under Pearson's leadership, the company has come under US government scrutiny for acquiring off-patent drugs and dramatically hiking the prices.

Valeant's US-listed shares, down about 20% this year, closed at $114.11 on Thursday.